Take the butter out of the fridge at least 20 minutes first and then put it in small pieces in the mug, whip up: 1 min. speed 4.
Add the cold cheese, whisk again: 1 min. speed. 4.
Add the vanilla extract and a pinch of salt, mix: 10 min. speed 4.
Then, with the blades moving at speed. 3, add the icing sugar a little at a time and whisk for another 2 minutes.
Refrigerate in a bowl covered with plastic wrap for at least 15-20 minutes before use (can be kept for up to 6 days in the refrigerator).
Garnish the cupcakes with a spatula or pastry bag. Serve immediately or refrigerate... Buon appetito!
For the colored version, just add some food coloring (powder or liquid) after letting it rest in the refrigerator and then garnish the cupcakes. If you only have spreadable cheese in a bowl (other than Philadelphia), drain it and dry it with a dry cloth, reduce it to “small pieces” and let it harden 5-10 minutes in the freezer.
*For those who are intolerant to dairy products, use lactose-free butter and spreadable cheese.